如何根据匹配的另一个字典键/值查询嵌套对象字典

nested_dict = {
    'key1': 'value1',
    'key2': {
        'key3': 'value3',
        'key4': 'value4',
    },
    'key5': {
        'key6': {
            'key7': 'value7',
            'key8': 'value8',
        },
        'key9': 'value9',
    },
}

def search_nested_dict(nested_dict, search_dict):
    for key, value in nested_dict.items():
        if key == search_dict['key'] and value == search_dict['value']:
            return value
        elif isinstance(value, dict):
            result = search_nested_dict(value, search_dict)
            if result is not None:
                return result
    return None

search_dict = {'key': 'key7', 'value': 'value7'}
result = search_nested_dict(nested_dict, search_dict)
print(result)  # 输出：value7